The Best Smart Thermostat

Emerson has issued a recall on certain models of our former budget pick, the Sensi Wi-Fi, with the model number 1F86U-42WF or UP500W and a manufacture date from 1416 to 1536 on the back.

Emerson has issued a recall on certain models of our former budget pick, the Sensi Wi-Fi, with the model number 1F86U-42WF or UP500W and a manufacture date from 1416 to 1536 on the back.

This recall affects about 135,000 units, which are believed to pose a potential fire hazard due to a wiring issue. If you suspect that you own an affected model, please contact the manufacturer, White-Rodgers, toll-free at 888-847-8742. You can also file a claim online at white-rodgers.com by following the “Emerson Branded Sensi Recall” link on the homepage.

Your guide

Jennifer Pattison Tuohy

We spent three months testing nine popular smart thermostats, and after considering design, features, ease of use, how comfortable they kept our home, and integrations with popular smart-home systems, the Nest Thermostat E is our top pick. The best smart thermostat is one that intelligently adjusts your home’s temperature with the least amount of programming, and like other Nest models, the E fits that description—it is simpler to use than any other smart thermostat we tested. And it’s significantly cheaper than previous Nest units, without sacrificing much functionality.

Buying Options

Like all Nest thermostats, the Nest Thermostat E learns your heating and cooling preferences and intelligently creates a schedule, adjusting your home’s temperature so you don’t have to fiddle with it yourself. It installs easily (though it's compatible with slightly fewer HVAC systems than other Nest models), works with Nest’s Temperature Sensors to help keep all your rooms comfortable, and blends in nicely with walls thanks to a clean, white design that some people may find more appealing than the previous black-and-metal Nest models. It also works with a wide variety of smart-home platforms, including Alexa and Google Assistant. It lacks a few features compared with the standard Nest model, but these are minor conveniences rather than necessities.

Buying Options

If a Nest Thermostat E is not compatible with your heating, venting, and air-conditioning (HVAC) system, or you want a smart thermostat with a bolder look or more features, Nest’s third generation smart thermostat is a good choice. It does everything the Nest Thermostat E does, works with a few more HVAC systems, and comes in four colors. It also offers a bigger, brighter screen, with more display options such as weather and a clock face. But when it comes down to it, the third-generation Nest controls your home’s climate in the same way as the Nest Thermostat E, for around $80 more, which is why it’s our runner-up pick—you should spend more for this one only if you prefer its design or really want those extra features.

Buying Options

Thanks to a built-in Alexa, the Ecobee4 can play music, relay the news, and control your home’s smart lights as well as adjusting the heat and air conditioning. Like other Ecobee thermostats, the 4 also works with remote sensors, which is useful if your thermostat isn’t in the best part of your house to measure the temperature: Ecobee4 uses the remote sensors’ readings, along with occupancy detectors, to achieve the target temperature in multiple occupied rooms, rather than just wherever the thermostat is installed. (One sensor comes with the unit, and you can add up to 32 more.) Because it has Alexa built in, you don’t need a separate Echo to control it by voice, and if Alexa isn’t your smart-assistant choice, Ecobee4 also works with Google Assistant and (via Apple’s HomeKit) Siri. However, it doesn’t have the level of intelligence of the Nest Thermostat E for automatically figuring out your schedule, and it’s worth spending the extra money on only if you have real issues with cold spots in your home, or really want an Alexa in your thermostat.

Buying Options

For a less-expensive smart thermostat with most of the important features of our other picks, we suggest the Honeywell Lyric T5. While it can’t sense your presence or learn your schedule, its built-in geofencing feature has improved dramatically since we first tested Lyric devices, and it works very well as a less-expensive way to manage your home’s energy use and climate. The Lyric T5 is also compatible with Apple HomeKit/Siri, Google Assistant, and Amazon Alexa.

Why you should trust us

I’ve spent the past five years living with and testing smart thermostats and other smart-home devices in my own home. I write extensively on how to save energy around the home, and my work on smart-home technology and sustainable living has appeared in Dwell magazine, Mother Earth News, Tech Republic, Triple Pundit, Network World, and Engadget, among others. I have written several smart-home guides for Wirecutter, including reviewing smart sprinklers, garage-door controllers, and smoke alarms.

Who should get this

A smart thermostat is for you if you are interested in saving money on your energy bills or want to control your home’s climate remotely, either from the couch or from the other side of the world. It will spend time doing the thinking that most people don’t do, so it can learn your household schedule through observation, turn itself down when nobody’s home, and target temperatures only in occupied rooms.

By intelligently managing your heating and cooling in this way, a smart thermostat can save you money: Nest claims that its learning thermostat saves enough energy to pay for itself in as little as two years. It can also help reduce energy usage for the good of the planet. According to Energy Star, which started rating smart thermostats this year, if every American household installed a smart thermostat, the energy savings would be equivalent to 1.2 million fewer vehicles on the road. Because of these dramatic savings, energy companies often offer rebates and incentives for replacing a traditional thermostat with a smart one.

Smart thermostats integrate well into a smart home, and all of the models we tested work with one or more smart-home systems, including Amazon’s Alexa, Google’s Assistant and Apple’s HomeKit/Siri, as well as with smart-home hubs such as SmartThings and Wink. This gives you voice control over your home’s temperature, as well as other automatic ways to adjust your climate control beyond the capabilities of the thermostat alone. For example, you can have your thermostat turn down when you lock your front door, or start warming the house when you open the garage. These smart ecosystems are continually growing, meaning the interactions your thermostat is capable of are growing as well (though sometimes only with the purchase of additional hardware).

How we picked

More than three dozen smart thermostats are on the market today, and that’s not counting all of the models specific to particular HVAC manufacturers. The category has exploded over the past five years, so to narrow down our list of models to test, we identified the six most important features of a smart thermostat:

Respond to your comfort and energy-saving needs (using algorithms, geofencing, or other smart senses) without you having to manually change the temperature setting.

Reduce energy use and save money on heating and cooling bills. Some smart thermostats are now Energy Star rated, potentially qualifying you for a rebate.

Be easy to use, both when operating the thermostat directly and when using a remote control (through an app, voice control, or smart-home integrations).

Offer useful integrations with smart-home systems—for example, automatically turning your lights off when the home is empty, or shutting down your HVAC system if there’s a fire.

Provide insights into your energy use so that you can adapt and save more.

Work with one or all of the popular voice assistants: Apple’s HomeKit/Siri, Google’s Assistant, and Amazon’s Alexa.

During our research, three categories of smart thermostats emerged: those that regulate your home’s climate completely autonomously; highly automated thermostats that still require user input; and basic, Wi-Fi–connected thermostats that offer remote control but no native automation.

Right off the bat we eliminated the last of these categories. While it’s useful to be able to control your thermostat remotely, such a unit is not truly smart, because you still have to do the thinking for it.

We also dismissed thermostats from HVAC manufacturers that are not compatible with other systems, or are available only through dealers, because these won’t work for most people and you can’t install them yourself. There may be one reason to consider a manufacturer-supplied smart thermostat, however: If you are getting, or have, a new HVAC system. Smart thermostats from HVAC manufacturers such as Bryant, Lennox, and Carrier have improved significantly over the past few years and are designed to work in perfect sync with high-tech new units. Check with an HVAC installer about compatibility and what benefits might be lost by not going with one of their thermostats. If you decide to use a Nest or Ecobee thermostat, make sure your HVAC installer includes a common wire, or C wire, to avoid the potential issues described below.

You should expect to spend between $130 and $250 on a smart thermostat. Lower-end models have fewer features (below $130 gets you a basic Wi-Fi thermostat but no smart features), while paying more generally means a thermostat will work with more systems and use higher-quality materials (though most options that cost more than $250 are overkill or are specific to particular HVAC systems). We eliminated anything outside of this price range; we found that the sweet spot today is around $170.

Taking all this into account, our final list of smart thermostats to test was:

Nest

Nest Thermostat E

Honeywell Lyric

Lyric T5

Ecobee4

Ecobee3 Lite

Sensi Touch

iDevices Thermostat

Lux Kono

How we tested

Photo: Jennifer Pattison Tuohy

We installed each thermostat ourselves in a 2,200-square-foot, two-story South Carolina home during late summer and early fall, and ran it for three to 10 days of routine operation. The home has a two-zone electric HVAC system, operating a heat pump (not a furnace) with two heating stages. During our testing we compared each device in 10 categories:

Overall appearance, design, and ease of use

Compatibility with a variety of HVAC systems, and whether a C wire is needed

Installation and setup

Companion app quality—user friendliness and available features

Home comfort—what’s smart about the way the thermostat controls your home temperature, and does it succeed?

Autonomy—how much user input does the thermostat need to maintain home comfort?

Processes for setting a schedule (if necessary)

Other smart features

Useful smart-home integration

Energy-usage reporting and insights, and do they really help save money

Buying Options

The standout feature of the Nest Thermostat E, as with all Nests, is that it automates the comfort of your home with little to no input from you, saving you money while keeping you cozy. But the E offers the same learning abilities, simple user interface, and compatibility with a wide range of smart-home devices as the standard Nest (third generation) for around $80 less. One of only three DIY smart thermostats we tested to be rated by Energy Star, the Nest Thermostat E is the simplest, smartest, most energy-efficient thermostat available today, at a great price.

The E comes with a default schedule but will learn and adapt to any adjustments you make, so after a week or so it will know your schedule (if you want it to). This learning feature is unique among the smart thermostats we tested, and helps the technology dissolve into the background. In our testing, we found that once the Nest Thermostat E had figured out our household’s patterns, we rarely, if ever, had to touch the device or adjust the temperature remotely. This feature is the primary reason we have chosen a Nest as our top smart thermostat for four years in a row.

One of only three DIY smart thermostats we tested to be rated by Energy Star, the Nest Thermostat E is the simplest, smartest, most energy-efficient thermostat available today.

Compared with the Nest (third generation)—our current runner-up pick and previous top pick—the Nest Thermostat E is smaller and lighter, swapping metal components for plastic ones and opting for a lower-resolution LCD screen with fewer visual features. The E’s face is also white instead of black, and it has six wiring ports instead of 10, but in all other ways our top pick is the same as the third-gen Nest. This includes having the same embedded sensors (temperature, humidity, proximity/occupancy, and ambient light); the E’s closest competitor in terms of price, the Ecobee3 Lite, lacks occupancy sensors.

The E is also compatible with the optional Nest Temperature Sensors, $40 white pucks you can place in different rooms and choose as alternate set points for your thermostat. Each sensor can pair with one thermostat (up to six per thermostat, 18 per home) and communicate with it over Bluetooth LE, up to 50 feet away. You can put a sensor on its own schedule, allowing you to prioritize different rooms at different times of day (for example, the kitchen when you’re cooking in the evening). For larger, older homes with inefficient HVAC systems, the ability to ask for more heating or cooling in individual rooms is an attractive feature, one reason for the success of Ecobee’s smart thermostat, which uses similar external sensors in this way. However, in our testing the Nest sensors merely confirmed that our HVAC system worked efficiently, as there was never more than a 1-degree difference between the sensors and the thermostat. We didn’t find much use for them, but if your system doesn’t work the way it should, these sensors will certainly help you patch the holes. The sensors are compatible only with the Nest E or the third-generation Nest thermostat.

The Nest Temperature Sensors display in the app along with the thermostat. Tap the thermostat, and you get a list of the temperature at each sensor. You can change the target sensor on the fly just by tapping the one you want, or set a schedule that will switch between a sensor and the thermostat.

To use the Nest Thermostat E, you turn the outer ring to adjust the temperature (or navigate on-screen menus) and press the screen to make selections. This is simple to do and won’t confuse guests or visitors, plus the smooth, ceramic-like ring feels nice in your hand and works consistently, which can’t always be said of touchscreens. The E’s display wakes up when you approach it to show you the set temperature and the current actual temperature. Pressing the screen gives you access to a quick menu where you can change the mode; see weather, time, and day; turn on the fan; and access the settings menu.

Its screen is frosted, which eliminates the greasy-fingerprint issue that plagues nearly all of the other models we tested (including the third-gen Nest). It’s still easy to read when you are in front of it, although we had to adjust our viewing angle a couple of times to see it clearly in some circumstances. We like the opaque look of this model because it’s less distracting and showy than other smart thermostats, and it went well with the gray and brown walls in our test home. Overall, the Nest Thermostat E appears as if it was designed to blend into your home rather than stand out—opposite of the standard Nest design.

Installation is straightforward—the E was the quickest and easiest to install of all the thermostats we tested. All you need is a screwdriver (unlike the third-generation Nest, the E doesn't come with one) for attaching the baseplate to the wall and your Wi-Fi password to connect the E to your network. The wires click in easily, and the device guides you through setup. You do need a basic knowledge of how your system works, but the device provides online links to useful information as you go through each selection if you are unsure.

Like its big brother, the Nest Thermostat E does not need a C wire to operate in most cases. Nest says the E is compatible with 85 percent of systems (check compatibility with your HVAC setup here), specifically excluding those that use a whole-house humidifier or have more than three stages of heating or cooling. For those, you need the standard Nest. However, if your system is compatible, there’s no practical reason to buy a standard Nest over the Nest Thermostat E.

Once installed, the device walks you through the process of checking if your wiring is correct, and then prompts you to choose your “eco temperatures” (what the system will set to when you aren’t home to save energy) and your preferred “home temperatures” (the warmest and coolest you want the house to be when you’re home, so it’s comfortable). You can then choose to connect to Wi-Fi, allowing you to use the excellent Nest smartphone app. The app lets you take advantage of geofencing and multiple smart-home integrations, and it allows you to control the temperature when you’re away from home—or just when you’re on the couch—but it’s not essential for operation.

The app displays the schedule that Nest has created; adjust it if you like, and view a 10-day history of the system’s energy use. You can also use the app to switch the thermostat between cool, heat, or auto mode. You adjust temperature on a large dial that mimics the device itself, and all of the same features are accessible on Nest’s online web tool or on the device itself. If you have other Nest products (such as cameras or smoke alarms) they also show up in the app.

Once it is up and running, the Nest Thermostat E starts working from a preset basic schedule, but you can (and should) turn on the auto-schedule feature, which tells the E to learn your habits through your manual adjustments (on the device or through the app), through presence sensing via its built-in occupancy sensor (and those of other Nest devices you may have, such as Nest Protect smoke alarms), and through geofencing using your smartphone. Nest uses this data to create and continually adjust a personal schedule for you. Nest is the only thermostat that manages your schedule in this way, removing entirely the pain point of having to program your thermostat. This makes it by far the easiest smart thermostat to use.

This is the default heating schedule for the Nest E. During setup you can choose to use the basic schedule or to have it auto-schedule for you.

Another essential smart feature of the Nest E is its Eco mode—a giant improvement on what used to be known as Auto Away. This feature uses a combination of presence sensing and geofencing to determine when the house is empty and thus when to activate Eco mode. You choose your preferred Eco mode temperatures when you set up the thermostat (but you can change them at any time), and the Nest E aims to keep your home between those temperatures to save you energy. When it senses you’re home/coming home, it returns to its schedule.

Many of the smart thermostats we tested use geofencing to adjust your home temperature and save you money, but only two manufacturers, Nest and Ecobee, also use presence sensing to inform this feature. This is important because geofencing alone has a major flaw: Anyone in your home without a smartphone connected to your system (children, grandparents, visitors), will be left in the cold if all the connected users leave the house. If you are single and live alone, this won’t be as much of an issue, but for larger homes or those with people coming and going a lot, it’s less than ideal.

Nest manages geofencing smoothly through a feature called Home/Away Assist. This uses your smartphone and anyone who is in the home (through occupancy sensing) to determine whether to go into Eco mode. It doesn’t go into Eco mode as soon as you leave, but instead waits (up to two hours) to make sure the house is empty. However, you can tell the E to go into Eco mode sooner, through either the app or other connected devices, to save more energy. When you come home, the E triggers earlier, and can even start before you arrive home. In our most recent round of tests, Eco mode activated more reliably than it had in our previous assessments of Nest thermostats (using Auto Away), and is a significant improvement over previous versions of Nest’s Away software. (Eco mode is available on all Nest models.)

The Nest E also saves energy through machine-learning algorithms that Nest claims (PDF) can model the internal thermal dynamics of your space. This process learns how quickly your home cools or heats and how your system performs, and then pairs that information with local weather conditions to keep your home comfortable. Its smarts can figure out that it’s colder today than it was yesterday, for instance, and start heating earlier to hit the target temp for 7 a.m., rather than simply turning on at 7 a.m., or 15 minutes before 7 a.m., as some of the thermostats we tested do. Additionally, features such as Cool to Dry and Airwave help combat hot summers by cooling to reduce humidity, and using the fan to eke out every last bit of cool in your system when the AC turns off, helping save energy and money.

Other notable features of the E include alerts in the app to warn you of potential problems and to tell you when to change your HVAC system’s filters. For example, you’ll get a message when your home has reached the Safety Temperatures you choose during setup, and a second message when things have returned to normal. Furnace Heads-Up also sends an alert if there’s an issue with your forced-air system’s filter, potentially avoiding costly breakdowns, and SunBlock adjusts the thermostat’s readings if it’s in direct sunlight (which can cause false readings).

Nest integrates with many smart-home devices and ecosystems to provide extra functionality. A few include Wink, Lutron, Alexa, Control4, Vivant, Insteon, and WeMo. (Apple’s HomeKit and Samsung’s SmartThings are two notable exceptions.) These integrations, which the company manages via the Works with Nest program, can enhance Nest’s learning algorithms’ data points, let you use the Nest as an occupancy sensor for triggering other devices, and allow devices to activate your HVAC system (such as Airwair, an indoor-air-quality monitor that can tell Nest to turn on the fan and circulate air if it senses a buildup of pollutants).

In the four years we’ve been testing Nest thermostats, we have tried many of these integrations. A few favorites include smart lighting that automatically shuts off when the Nest senses you’re away, and smart blinds that open and close in sync with Nest to manage solar heat gain in your home. But in terms of helping your system save energy, integrating with a smart door lock is one of the simplest, most useful integrations. The Kevo by Kwisket, for example, pops up a prompt on your smartphone to set your Nest to Away (Eco mode) when you lock it and to Home when you unlock. This was more practical in our test home than, say, the connection to the MyQ Smart Garage Door Controller, because you generally only lock or unlock your door when you leave or arrive, but you may open or close a garage door when you’re not leaving. From a safety angle, the ability to tie in your smart smoke alarms with your Nest is a great benefit. Using Nest Protect smoke alarms (or IFTTT integrations with other smart smoke alarms), you can trigger your HVAC system to shut down if a smoke or fire emergency is detected, potentially helping stop the spread of the fire.

You can also control the E with your voice using Amazon’s Alexa smart speakers and Google’s Assistant, through Google Home, or your smartphone (Android or iPhone via the Google Assistant app). While we found voice control useful for the other thermostats, we rarely used it with the Nest, as the automatic settings worked pretty seamlessly. But if voice control is important to you, the E has a much deeper integration with Google than with Alexa, as both Nest and Google are owned by Alphabet. The Alexa commands are limited, and it’s a bit tricky to get the nomenclature right; you also can't use Alexa to activate Eco mode or switch between heat and cool.

With Google Assistant you can do all of the above, including turning your HVAC system on or off or to auto (though you still can’t turn it to Eco mode). We found it much easier to talk to Google, as you can use more-natural language than with Alexa, and even carry on a conversation—such as to ask what the temperature is upstairs, then act on that info by saying, “Make it warmer.” It’s not obvious how to connect your Nest to Google Assistant (either on your phone or to the Home speaker), so follow this guide.

Chatting with Nest through Google Assistant, which you can do on your phone or using Google Home, is a more natural process than with Alexa.

We also evaluated the energy usage reporting the Nest E offers, and looked at how this information can help you save money. This is one area where every device we tested was drastically different. Some have no reporting, others have everything you could possibly want, and the rest, like Nest, are somewhere in the middle. The Nest E offers a 10-day history in the app and online that shows you when the system was set automatically or manually and to what temperature. This is useful to see how your system has been performing and whether Eco mode has been activating, but it’s not deep-dive information if you want to micromanage your energy use. You also receive a monthly energy report in your inbox.

The most useful insight Nest offers is its green leaf, a visual indication or affirmation whenever you set a temperature that the Nest says is an energy-saving one (based on your heating and cooling history and Nest’s data). “You can’t discount the psychological power of Nest’s green leaf icon,” said HVAC contractor Bronson Shavitz, who has installed and serviced hundreds of heating and cooling systems over the years. “[This] motivates you to forgo a little comfort and dial the temperature down just a little bit more in order to save energy.”

Flaws but not dealbreakers

The main reason for the $80 price difference between the Nest Thermostat E and the standard Nest is that the E’s screen is a step down in hardware terms. The E’s frosted screen is more muted than the standard Nest’s high-res color display, which looks more like a smartphone’s. The E’s display also has fewer features. With the standard Nest you get a bold, brilliant display you can see from across the room, thanks to a feature called Farsight. You can also customize the standard Nest’s screen to show the weather or a clock face when the screen is in standby mode; the Nest E can show only the current indoor temperature until you get close or touch the display.

The Nest E’s main feature—the ability to learn your schedule—is not without its flaws. The learning period is slightly different from that of the Nest (third generation), because the E comes with a preset schedule that it adjusts based on your changes, as opposed to starting with a blank slate and building from there. In our first few days of testing, the E adjusted itself back to its schedule immediately after being told to do something else. This was initially frustrating, but stopped within a couple of days.

We’ve seen owner reports of Nests doing crazy things, such as cooling a home to 50 °F on a cold winter’s morning. We came across a similar issue when one of our test units set up an auto-schedule for the upstairs zone to heat to 81 °F midmorning, then to 66 °F in the evening. It was during a seasonal change, and the temperature set point for the thermostat during the day had been at 81 °F cool to save energy. The Nest E translated that to 81 °F heat when we switched the mode from cool to heat. It was a shock to see the heat try to go from 66 °F to 81 °F on a cool October morning. To fix the issue, we deleted the schedule the Nest had set and told it to relearn, which it did much more efficiently the second time.

The new Nest Temperature Sensors are sadly one-trick ponies. They measure temperature, and that's it. Why they don’t also sense motion is as confounding as why Nest’s Protect smoke alarms don’t sense temperature. A motion sensor in there would have allowed Nest to offer a “follow me” feature like Ecobee’s, which adjusts your thermostat to where you are in the house. This is much more intuitive than Nest’s system of programming each sensor based on where you think you might be at a certain time of day.

Nest also doesn’t work with HomeKit and is the only smart thermostat we tested that isn’t compatible with Apple’s smart-home system.

Buying Options

We still love Nest’s third-generation thermostat, previously our top pick. Its striking design and (along with the Nest E) unmatched smarts make it an excellent thermostat. But unless you have a more-complicated HVAC system (for example, three-stage heating, two-stage cooling, three-speed fans, humidifiers, and other similar add-ons) that the E is not compatible with, there’s no practical reason to spend the extra $80 for the third-generation model over the Nest E.

That said, if you are looking for a particular design aesthetic, this Nest is the most visually striking thermostat we tested. It’s the only model not made entirely of plastic, and its tactile metal ring feels substantial and high-end. Its screen is larger than the Nest E’s, with a 480×480 resolution and 229 ppi display density (compared to 320×320 and 189 ppi on the E), resulting in crisper text and a more-attractive interface. It’s a significant step up from the Nest E’s frosted screen, assuming you want a bright, more visible thermostat screen in your home.

As part of that visual difference, the third generation offers a feature called Farsight. The Nest E and previous Nest models light up when they sense you are in front of them, but this model can illuminate when you are farther away, such as when you enter the room. It’s nice to be able to see the temperature from across the room, but by no means a necessity. The best feature of Farsight, we think, is the capability to choose what the screen displays when it’s not in use: You can opt for temperature, weather, or time (using a digital or analog clock face), which you can’t do on other Nests. The third generation’s display also turns red when its heating and blue when its cooling, giving you a clear visual cue of what your system is doing no matter where you are in the room.

Nest third-gen has Farsight, which allows you to choose between clock faces, temperature, and weather when the thermostat is not in use. Photo: Jennifer Pattison Tuohy

In other respects, the third-gen Nest and the Nest E are identical: They have the same learning capabilities, both are compatible with Nest’s Temperature Sensors, they have the same smart-home integrations, and they will manage your home’s heating and cooling identically. The only other minor difference is that the standard Nest has a learning period when you first install it—you have to manually adjust it for the first few days—during which it figures out a schedule for you, whereas the Nest E comes with a preset schedule it uses out of the box, requiring no input from you. If you do change the temperature though, the Nest E will learn and adapt its schedule to your needs just like the other Nest. (If you want one of Nest’s neat little white screwdrivers, you have to go for the more expensive Nest: Part of the Nest E’s reduced price includes stripped-down, slimmer packaging and no handy magnetic screwdriver.)

Buying Options

While the Nest and Nest E are our top picks in large part due to their stylish simplicity, the Ecobee4 is our upgrade pick for the opposite reason: This is a complex piece of equipment that can do everything you might want your thermostat to do, as long as you take the time to read the manuals (plural), forums (multiple), and support articles (endless). We recommend it for those who want deep-dive control over their energy use; are looking for robust integration with smart-home systems that Nest is not compatible with; or who want to add an Alexa smart speaker to their home.

The Ecobee4 has four distinctions over the Nest E that push it into the “upgrade” category, but bear in mind that you’re paying significantly more for these upgrades, especially if you want more than one remote sensor:

Remote sensors: The Ecobee4 manages your home’s climate using its built-in sensor and any remote sensors you add (it comes with one); together the sensors allow the thermostat to monitor two or more areas in one zone (it cannot manage two zones). This arrangement promises to help fix the age-old heating and cooling problem where one room is toasty and warm while another feels like a refrigerator (or vice versa in the summer). Ecobee’s remote sensors are better than Nest’s because they are also motion sensors, so the thermostat can follow you through your house, focusing its efforts on the room you're in just by your being there, no need for you to do anything.

Built-in Alexa smart speaker: Alexa is integrated into the thermostat, a welcome feature if you don’t already have an Echo or Echo Dot Alexa speaker, or if you want to add Alexa’s capabilities to the area of your house where your thermostat is.

In-depth usage history and energy reporting: Ecobee offers (after the first month of use) extensive insights and real-time updates of your energy usage and thermostat set points through the HomeIQ feature on its web interface.

The Ecobee4 is a sleek, black-plastic box—in contrast to the simplicity of the unobtrusive Nest E, the Ecobee4’s rounded-rectangle design looks like a smartphone app on your wall. It is bigger and chunkier than previous Ecobee thermostats (roughly twice the size of the Nest E) and protrudes from the wall farther to make room for the built-in Alexa speaker and mics. The touchscreen interface, unchanged from the Ecobee3 (which is discontinued), has a more modern feel than Nest’s dial-and-press system, but it’s also more finicky, and it’s difficult to select the temperature you want on the sliding scale. The 4’s screen size is the same as on previous Ecobee models, but with a few extra on-screen buttons related to Alexa.

The Ecobee4 is compatible with the same number of HVAC systems as the Nest offerings, including those systems with humidifiers, dehumidifiers, and ventilators (check compatibility with your system here). It does require a C wire but comes with a power-extender kit and detailed instructions for how to wire it to your HVAC system if you don’t have one. It is also Energy Star rated, potentially qualifying you for a rebate.

Installing and setting up the Ecobee4 was the most involved of all the units we tested, largely because there are so many smart-home systems to connect to. It took us an hour in total, but if you have to wire in the power extender kit, factor in an extra two hours.

The Ecobee4 offers two main ways to control your climate:

Temperature/occupancy sensors in the device and in remote sensors: It comes with one sensor, but you may want to buy more (our test home is 2,200 square feet, and we used three sensors to keep tabs on the upstairs zone alone). These let you trigger your heating and cooling based on temperatures and occupancy in certain rooms in your house. (You can’t set different temperatures for different sensors, but you can configure the system to prioritize occupancy using the Follow Me feature.)

Based on a preset sleep, home, and away schedule (which you can tweak): That schedule, however, will revert to your configured Smart Home/Away temperatures if any of the sensors determine that you are home when the schedule thought you would be gone, or vice versa.

In our testing, both of these features worked well to maintain the home at a comfortable temperature while not using too much energy. However, there’s one big caveat: If we changed the temperature manually in any way—on the device, in the app, or by talking to Alexa or Siri, for example—the system went into a so-called indefinite hold. This meant that it remained at that temperature until we manually changed it (on the device or in the app), regardless of schedules or occupancy activity.

If you don’t understand this behavior and don’t manually choose Resume schedule, you can end up wasting a lot of energy heating or cooling when you don’t want to. To avoid this, you need to change the default hold action in the setting from Indefinite to either a timed delay or Until the next scheduled activity. But there’s another caveat: If you make any change with Alexa or HomeKit, your system will go into an indefinite hold no matter what hold action you have chosen. This means you have to remember to tell Alexa or Siri to “Resume schedule”—you can’t rely on any of your thermostat’s smarts to do it for you.

A third option for control is geofencing, which, as with Nest, you can choose to enable to improve the built-in occupancy sensing. This feature is mainly designed to be used instead of a set schedule and is most useful if your personal schedule is erratic. Geofencing works with the Android app natively, but if you’re using an iPhone, you need to go through HomeKit, which requires a gateway (such as an iPad running iOS 10 or higher, a fourth-generation or later Apple TV, or Apple’s forthcoming HomePod). Another option is to use IFTTT, but IFTTT was not reliable in our testing.

Alexa integration is one of the main features of the Ecobee4, and while the Nest Thermostat E works with Alexa, the Ecobee4 is tightly integrated with the voice assistant, and not just because Alexa is built into the device. The Ecobee’s Alexa Skill, Ecobee Plus, gives you more control over your thermostat with your voice than Nest’s, allowing you to do things like ask Alexa which equipment is running or request temperature readings from your remote sensors, and even ask Alexa to set a vacation for you. The downside of Ecobee Plus is the clunky nomenclature: Every command requires you to start with, “Alexa, ask Ecobee to …” The original Ecobee skill (which is still available) lets you simply say, “Alexa, set the thermostat to 68 °F.”

This is partly because the built-in Alexa is not tuned specifically to the Ecobee4—it’s just a regular Alexa in the thermostat—so you still need to use that specific language. One advantage is a Push to Talk button on the Ecobee4, which gives you the option of skipping the wake word (Alexa). While Alexa can hear very well, you’re not going to be having any dance parties using this speaker, as the sound is best described as tinny. But you can use it for anything else you might want to use Alexa for: to set timers, ask about the weather, control your other connected devices, and so on. One other limitation is that you can’t change the wake word from “Alexa.”

Integration with Apple’s HomeKit smart-home platform sets the Ecobee4 apart from the Nest E if you are an iPhone or iPad owner. You can circumnavigate the Ecobee app entirely and access your thermostat settings from the iPhone’s Control Center with a quick swipe. From there, you just drag a slider up or down to adjust the temperature—this was our preferred method of controlling the Ecobee4 when using an iPhone. HomeKit also lets you control the thermostat by voice with Siri, implement geofencing, and unify all your HomeKit devices through scenes, such as Good Morning and I’m Home, to trigger desired temperature settings, turn lights on or off, and/or lock and unlock doors. The biggest issue with HomeKit and the Ecobee4 is, as described earlier, by using it you put the Ecobee into an indefinite hold mode, so you have to choose a Resume schedulescene to get your thermostat back into its usual mode—and remember to use that scene.

In addition to offering compatibility with Alexa and HomeKit, the Ecobee4 also works with SmartThings (which the Nest E does not, natively), Google Assistant, and pretty much every other smart-home system out there. However, to get the most out of all (or probably just one or two) of these integrations, you face a steep learning curve. If you want a thermostat you can just put on your wall and forget about, the Ecobee4 is not that. But if you want deep control over every change your thermostat makes, the Ecobee4 gives it to you.

Buying Options

Honeywell’s Lyric T5 is the least expensive smart thermostat we’ve tested that we can highly recommend. While it can’t sense your presence in the home and it doesn’t learn your schedule, it offers many of the features you might look for in a smart thermostat, including smart scheduling, native geofencing, integration with the major smart-home platforms, and an Energy Star rating. If you are specifically looking for a thermostat to use with Alexa, Google Assistant, or Siri, and don’t need the advanced capabilities of a Nest or the Ecobee4, the Lyric T5 is a good option.

The Lyric T5 edged out our previous budget pick (the Ecobee Lite, which works with all of the same systems) because it is less expensive. Also, Ecobee Lite requires at least one extra sensor (or a HomeKit hub) for occupancy sensing to work optimally, bringing its price closer to $200—nearly twice as much as the Lyric T5. The Lite does offer energy and usage reporting, however, which Lyric T5 does not.

Lyric T5 is a good-looking, if very large, thermostat. A sleek black box with white fonts on a black screen, it resembles a digital alarm clock. Compatible with most 24-volt conventional forced air, heat pump, hot water, and steam heating systems, it supports two-stage heating and cooling, but not humidifiers and dehumidifiers. It does need a C wire.

Installation is straightforward, and the device walks you through enabling geofencing, and setting the temperature you want for Home, Away, Wake Up, and Sleep. You use the Lyric smartphone app to pair the thermostat with HomeKit and connect to Wi-Fi. In our initial testing, we had issues with the device disconnecting from Wi-Fi, but after a reset we had no further problems. The big, black screen does get dirty quickly, but a “clean screen” option gives you 30 seconds to wipe it down without sending your thermostat haywire.

The screen displays the time and current temperature until you touch it, which in our testing required a quite forceful touch, and sometimes more than one. It then displays the time, target temperature, current temperature, and plus and minus buttons for easy temperature adjustments. Home, Away, and Sleep shortcuts, the current mode, and options for switching to Off, Cool, Heat, Emergency Heat, and Fan modes are also all crammed onto the home screen. Honeywell certainly doesn’t waste any of that screen real estate, which is good, as the way you scroll through and select other options is clunky and unintuitive.

The Lyric T5 controls your climate using geofencing, by monitoring the location of your smartphone and the phones of anyone else in your household. (This is a flaw if any of your household members don’t have a smartphone.) Based on your location and time of day, it then sets either your Home, Away, or Sleep temperatures. This worked well in the downstairs zone of our two-story test home. However, we turned off geofencing for the upstairs and just used a programmable schedule (the upstairs is not occupied during the day so there’s no need for it to heat or cool, even if someone’s home). You can’t have a schedule and geofencing enabled on the same device at the same time, something that was true of all the thermostats we tested, apart from the Nest and the Ecobee models.

Setting a schedule in the Lyric app is very straightforward, and far simpler than doing it on the device, with its scrolling menus that look like a Speak and Spell. Choose from Every Day schedule or Weekday and Weekend to start with, and you get a preset schedule you can adapt to your needs. One interesting feature of the Lyric T5 is the option to turn on the Auto Changeover feature, letting it decide when to switch to Auto mode (where your thermostat switches between heat and cool automatically). All the other devices we tested require you to manually select Auto mode, but Lyric T5 does it automatically, maintaining your desired heating or cooling settings no matter what is happening outside.

Caveats and C wires

A few things to know about smart thermostats before you buy:

If you have more than one climate-controlled zone, you will need to buy one thermostat per zone. (Even though Ecobee and Nest support remote sensors, those sensors feed to a single thermostat, not to the HVAC system as a whole.)

Not all models will work with all systems. In particular, systems with whole-house dehumidifiers, heat pumps, and ventilation systems will work only with the higher-end thermostat models. Check the thermostat company’s compatibility tool online before purchasing one, and pay careful attention to your existing wiring, as this will determine how well or if a smart thermostat will work with your system. (Checkthis page for system compatibility with Nest, and this page for help with wiring.)

If your thermostat does not have a C wire, you will need to choose your smart thermostat carefully. Read on ...

A C wire is the common wire that supplies AC power from your furnace to the thermostat to power the screen, among other things. Some thermostats, including Nest models, can work in the absence of a C wire, instead charging by stealing power from other wires. However, that can cause serious side effects, according to HVAC contractor Bronson Shavitz. He told us that old-school furnaces are generally resilient enough to provide power for devices such as the Nest and the Lyric, but that the high-tech circuit boards on newer furnace models can be more prone to failure when they’re under stress from the tricks these devices use to charge themselves without a common wire. If the power handling is not correct, the damage to your system can be significant: The expense of replacing a furnace or AC board, plus the cost of professional installation, will outweigh the convenience or energy savings of a smart thermostat. Nest addresses the power requirements of its thermostat, including whether a C wire is necessary, in detail on its website, so if you’re unsure whether your system is suited for it, check out this page.

There are a few other solutions to the C wire conundrum. You could have one installed by an electrician for about $150; Ecobee and Kono both offer the option of hardwiring a power extender kit to your HVAC system yourself; and some smart thermostats claim to work without one, but take that with a grain of salt. For example, Emerson’s Sensi Wi-Fi doesn’t need a C wire, but it draws power from whichever system is not currently in use (for example, the heating system if you’re using the AC). This means that if you have a heat- or air-only system, you will still need a C wire.

What to look forward to

Over the past couple of years there haven’t been significant advances in how smart thermostats control your climate. The future of smart climate control may well lie in the way smart thermostats integrate with smart vents. The idea here is that through connected vents, a system can monitor and personalize the temperature in each room, using built in occupancy and temperature sensors, rather than the house as a whole. Both Nest and Ecobee currently integrate with Keen Home Smart Vents, which promise to balance your home’s temperature proactively. Other competitors in this area include Ecovent (which has partnered with Emerson’s Sensi) and Activent.

Fans of Microsoft’s Cortana voice assistant haven’t been left out in the cold, thanks to the Glas Smart Thermostat from Johnson Controls. The Glas features a unique translucent design and claims to be the first thermostat to track indoor and outdoor air quality as well as to regulate temperature. And of course, it works with Alexa and Google Assistant as well. We plan to test it soon to find out if it's really worth the $320 price tag.

At the 2018 CES trade show, Nexia launched the Trane XL724, a touchscreen smart thermostat that can be controlled remotely via smartphone, tablet, or computer. We’re interested in testing the Trane XL724 when it comes out in 2018.

The competition

The Lux Kono is the new thermostat from the makers of LuxPro Geo, which is a basic smart thermostat under $100 that works without a C wire and uses geofencing to control your climate. The Kono takes everything its predecessor does and bumps it up a notch (for about $50 more), adding HomeKit compatibility. Its unique design features changeable faceplates that come in multiple colors to fit your decor (including a paintable one), and it uses a click wheel and a small screen for the display, rather than a touch screen. This interface is not intuitive, however, and you have to learn how to control it (there are some “notes” under the removable screen plate to jog your memory).

The Kono works with HomeKit, and as you go through setup it tells you not to set a schedule if you are going to use HomeKit. If you choose a schedule, it walks you through selecting one that fits your household’s lifestyle and one that fits how much energy you want to save. This is a neat feature that continues throughout the app: Every time you change your temperature, it tells you how much your energy costs will increase or decrease based on that change. Kono has built-in geofencing (using your phone) that will interrupt the schedule when it senses you have left.

Like the LuxPro Geo, the Kono doesn’t require a C wire, so if you don’t have one, you use the included power bridge to essentially plug your thermostat into your HVAC system (as with Ecobee). We did like this thermostat, but a few factors kept us from recommending it, including the app, which while clear and user-friendly feels clumsier than and not as elegant as the competition. The device itself is also way too big with a lot of wasted space given the tiny screen, and the click wheel is annoyingly loud. Kono’s real-time energy usage reporting was good, however, displaying its recent runtime prominently in the app. Kono also works with Alexa and Google Assistant.

The Emerson Sensi Touch is an upgraded touchscreen version of the Sensi Wi-Fi (a previous budget pick in this guide), both of which are HomeKit, Alexa, Google Assistant, and Wink compatible. They have the same capabilities, with the main difference being the screen and C wire needs. Sensi Wi-Fi is a pedestrian-looking device, similar in style to a standard programmable thermostat, and only worth considering if you can’t get any C wire options to work with your system. In December 2018, the company also issued a recall for certain Sensi Wi-Fi models manufactured between April 2014 and September 2015. By that time, it was already discontinued, and we no longer recommended it anyway; but if you did purchase one, you should visit the Consumer Product Safety Commission website for more information on the recall.

Sensi Touch does require a C wire, but it’s much better looking than the Sensi Wi-Fi, and the touchscreen is easy to use. It’s also simple to install—courtesy of a lighted backplate—and the large display is straightforward to navigate and easy to read, lighting up red or blue when heating or cooling. You can do everything you might need to on the device itself, so the smartphone app isnʼt really required beyond the initial setup, meaning you can file it away and just use your SmartHome service or Wink hub to control it when you need to.

Neither Sensi is smart enough to compete with Nest or Ecobee, and though they both have native geofencing as an option over a fiddly schedule setup (you have to set separate ones for heating and cooling), there’s no option for customized geofencing or set temperature points for home/away/sleep—instead it simply sets your thermostat back 3 degrees when you exit a 3-mile radius.

Ecobee3 Lite is Ecobee’s budget version, but its lack of any occupancy sensors (there’s not even one in the device) means it’s too stripped down for us to recommend it as a budget pick. Ecobee did add the capability, via an update, for the Lite to work with remote temperature/occupancy sensors, which definitely makes it a better thermostat, but once you buy two sensors (to bring it to the same level of usability as the Ecobee4, which comes with one and has another in the device itself), you end up paying nearly the same price.

The Lyric Round was Honeywell’s first foray into a geofencing smart thermostat, and design-wise it’s very appealing. But as with the Nest and Nest E, there’s no reason to buy this one over its less expensive sibling, the Lyric T5, unless you have a complicated system (it’s compatible with more) or the space-age, circular, white design fits better with your home’s aesthetic. In nearly all other respects they are the same, including HomeKit, Alexa, and Google Assistant integration, although Lyric Round’s interface feels more modern and less fiddly than the Lyric T5’s.

The basic-looking iDevices Thermostat works only with Apple’s HomeKit (and if you don’t have a HomeKit gateway you can’t control it from outside the home). Its tiny screen is glaringly bright with no option to dim it, and is blank when not in use. It has old-school, screw-in wires that feel very dated, but still needs a C wire. Its on-device UI is confusing to use, and the physical buttons don’t light up, so you can’t see them in the dark. Its smarts come through HomeKit’s geofencing, otherwise it’s just a programmable thermostat.The process for setting a schedule is supposed to be really user-friendly (showing you stock photos of people leaving for work, or arriving home), but actually changing any set schedule is hard to do, and there’s no way to see an overview of your whole schedule in the app. There’s also no energy-usage reporting. Unless you are deeply invested in iDevices products, this is one to avoid.

Wirecutter is a list of wonderful things by Brian Lam and friends, founded in 2011 and a part of The New York Times Company since 2016. Have a question? Just ask.